S. Davies, P. Španěl, David R. Smith
Jul 1, 1997
Citations
5
Influential Citations
326
Citations
Quality indicators
Journal
Kidney international
Abstract
The distinctive odor of the breath of patients with renal failure, usually termed the "uremic fetor," is frequently described as ammoniacal, and its potency is generally believed to reflect the uremic state [11. Previous attempts at breath analysis in these patients has, however, been directed at compounds other than ammonia, such as dimethylamine and trimethylamine, and have been at best semiquantitative in their approach [2]. This reflects the considerable methodological difficulties surrounding the accurate measurement of these compounds on breath. When they are present in low concentrations as part of complex mixtures, the value of conventional methods such as gas chromatography and mass spectrometry is limited because they usually require that the breath is pre-concentrated [3—SI. The selected ion flow tube (SIFT) technique is ideally suited for the accurate measurement of trace gases, particularly when present in complex mixtures [6—81. In contrast to conventional mass spectrometry, in which ionization of the trace gas molecules is achieved by electron bombardment, resulting in molecular "cracking" that yields spectra that are difficult to interpret, the SIFT technique exploits the method of chemical ionization. Molecules (M) present on the breath are "soft" ionized utilizing a precursor ion, such as H3O, which usually results in a single product, MH, which can then be detected by a mass spectrometer, thus allowing identification and quantification of trace gases with a sensitivity of 10 to 20 ppb from a single breath exhalation